Is the clamp ammeter not accurate enough? what is the real reason
Clamp ammeter electricians are very familiar with it, because it does not need to be connected in series in the circuit to measure the running current, which is safe and trouble-free, so it is one of the necessary tools for electricians.
The principle is actually very simple, that is, the combination of electromagnetic ammeter and current transformer. The old-fashioned clamp meter could not measure DC current before, but now, the new type can not only measure DC current but also AC current.
Those who have used the clamp meter will have a feeling that the number on the meter will jump when measuring, and the pointer on the pointer meter will also have a slight swing of the pointer, which will inevitably increase the measurement error. Although the error is inevitable, it can still be effective from the following points. reduce the measurement error. To learn more about clamp ammeters, please pay attention to the WeChat public account "Electrician Electrical Learning".
First of all, it is necessary to choose the range of the meter. This requires knowing the size of the current to be measured before the measurement. Of course, this is only a rough estimate. This is similar to the use of a multimeter. Estimate the approximate current, and then select Appropriate range measurement, large range measurement of small current will easily produce larger errors, and the measurement value is changing and it is not easy to determine.
Secondly, because the clamp meter has openable jaws, and the jaws are easy to be stained with dust during our work, resulting in poor sealing of the jaws, the jaws must be kept clean before use, and there is another situation Even if the watch has been used for a long time, the spring force is insufficient or the jaws are offset, which will also affect the measurement.
Again, to avoid the magnetic field, I have measured the overcurrent on the side of the autovoltage regulator. Every time the clamp meter moves a little, the value of the meter can have a lot of error. For the environment with strong magnetic field, it must be avoided when measuring. The exclusive original manuscript of Electrician Learning Network All rights reserved.
Again, in many cases, we think that it is enough to clamp the wire into the clamp hole. In fact, the closer the wire is to the center of the hole, the more accurate the measured value will be.
Finally, if the measured current is very small, the measurement error can be reduced by "winding the meter", that is, winding the measured wire a few more times in the bayonet of the clamp meter, reading the value, and then dividing it by the clamp meter The number of turns of the upper wire winding is the current value to be measured. This is often used in practice, and it is also a method to avoid large-scale measurement of small currents.
